Now Commenting On:

Pipeline Perspectives: Walker boasts top arm

Pipeline Perspectives: Walker boasts top arm

There's a good amount of subjectivity regarding baseball prospects. With the evaluation of talent being in the eye of the beholder, finding consensus is often difficult. Even Jim Callis and Jonathan Mayo at MLBPipeline.com don't always see eye-to-eye. They'll be discussing their viewpoints regularly in a feature called Pipeline Perspectives. Submit a topic for them to debate.

Last week in Pipeline Perspectives, Jim Callis and I debated which hitting prospect will have the largest big league impact in 2014. This time around, we're looking on the mound for pitching prospects we believe will make significant contributions in the Major Leagues next season.

Walker, a two-time Futures Gamer, really put it all together this year. A tremendous athlete who was a supplemental first-round pick of the Mariners in 2010, he found a level of consistency on the mound that allowed him to begin the season in Double-A and finish it in Seattle.

Along the way, he topped the Mariners system in strikeouts while finishing in the top five in ERA, batting average against and WHIP. Oh, and he didn't turn 21 until mid-August. Considering he was a raw, projectable high schooler three years ago, in many ways he is far ahead of the curve.

Walker has always had electric raw stuff, headlined by a plus fastball. He's become a more complete pitcher, showing a more consistent breaking ball -- a curve that will be at least above-average, if not better -- and developing a solid changeup to go along with it. As he's moved up the ladder, he's kept his walk rate constant, about 3.6 per nine, though it spiked a little with the move to Triple-A.

He certainly didn't seem overmatched or intimidated when he got his first call-up to the big leagues for the season's final month, winning his debut by giving up just one unearned run over five innings. He got to make one start at Safeco Field before the Mariners shut him down. At that point, he had amassed 159 1/3 innings, nearly 23 more innings that his career high in 2012.

Walker has proven to be strong and durable and should be the type who won't have any issues shouldering a Major League starting workload. He's also shown an ability to make adjustments. The Mariners challenged him with a double jump to Double-A to start the 2012 season and he took some lumps there, especially at the end of the year. Rather than sulk when he was sent back to the same level to start 2013, he proved to the organization that he could dominate the level and moved up.

That bodes well for him in Seattle. He'll invariably run into some stumbling blocks during his rookie season and how he bounces back from those rough outings will ultimately dictate how much success he has right away. During his time in Double-A this year, he responded to any start in which he gave up more than two earned runs with a start in which he held the opponent to no more than one earned run. In Triple-A, after a stretch in which he scuffled a bit -- giving up 20 earned runs over five starts -- he yielded just one run over his final two outings before his promotion.

It's difficult to imagine a scenario in which Walker won't be given every opportunity in Spring Training to win a job in the Mariners rotation. Seeing him eventually settle in as the No. 2 guy behind King Felix doesn't sound like an unreasonable expectation. I'm not saying that's going to happen right away, but Walker is poised to make a large contribution as a mainstay in the rotation all season and becoming a serious American League Rookie of the Year Award candidate.

Jonathan Mayo is a reporter for MLB.com and writes a blog, B3. Follow @JonathanMayoB3 on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.